The present invention relates to an information retrieval system and, more particularly, an information retrieval system equipped with a random-accessible memory medium such as a video disk.
Recently, electronic devices called electronic dictionaries have become available on the market. The electronic dictionaries require efficient and rapid retrieval of word information stored in a ROM. An example of such electronic dictionaries is disclosed in Levy U.S. Pat. No. 4,158,236, June 12, 1979, "ELECTRONIC DICTIONARY AND LANGUAGE INTERPRETER". The disclosure of this patent is incorporated herein by reference.
Since the capacity of the ROM is limited, it is desirable to replace the ROM with another type of memory. In this respect, the video disk is worth considering. Since the video disk is random-accessible, it might be employed as part of an improved information retrieval system.
However, a practical system suitable for retrieving information such as word information processed in the electronic dictionary has not previously been proposed.
In the video disk, the information such as the word information must be memorized in the form of digital codes. In such a case, careful consideration should be directed to the problem that dust on the video disk may cause error in reading out the video disk.
Further, when the video disk provides a still picture, the same tracks of the video disk are repeatedly traced, so that it was impossible to simultaneously speak the work information. This was a disadvantage for the electronic dictionary. Since, in a single track of the video disk, the visual signals forming a single still television picture, the aural signals and the address signals are superposed, the repetition of the tracing on the same single track provides the single and still television picture. However, because the round length of the single track can be traced for a very short time, about 30.sup.-1 to 60.sup.-1 sec., the data of the aural signals developed in accordance with the tracing of the single track are too small to provide pronunciation, as one reads, with the data. The reproduction of the data may cause only noise.